PLB
From Accident investigation of Sykorsky S92 near Newfoundland 2009, PLB specific:::
The PLB design is such that over-tightening of the antenna could, with very little resistance, cause the antenna connector to turn. If tightening is continued, the wires running from the connector will eventually break. Three of the PLBs recovered following the occurrence and examined by the TSB had loose antenna connectors, which would have prevented them from being watertight. Two of those three PLBs had twisted wires, one of which had the wires twisted until they broke. The broken wires would have made this PLB incapable of transmitting a signal. The third PLB antenna connector, which was recovered from the survivor, was likely damaged prior to the occurrence.
The manufacturer’s website states that the beacon is protected against the effects of immersion in water to depth between 15 cm and 1 metre. All of the recovered PLBs had contamination due to salt water ingression. The PLBs are electronic components and must be sealed from moisture to ensure correct operation. Since none of the search and rescue aircraft that responded to the occurrence received a transmission on 121.5MHz, it is likely that sea water quickly penetrated the PLBs, rendering them inoperable.
The flight crew were equipped with ACR AEROFIX 406 PLBs (part number 11-07709), which are small lightweight devices that were carried in their immersion suit leg pocket covered by the pocket flap. These PLBs transmit a 406 MHz signal that is detected by the COSPAS-SARSAT satellite system, and includes a registered unique, digitally coded distress signal. The 406 MHz beacons also transmit on 121.5 MHz to allow for traditional homing by SAR resources. The flight crew’s PLBs were not recovered by the TSB